Prostate cancer is a typical male cancer occurring at old age, and has increased also in Japan due to the aging of the population and the westernization of life style. In addition, an upward trend thereof has been confirmed because of an advanced blood test using tumor markers (prostate specific antigen: PSA) and a more generalized medical examination. When the age-adjusted incidence rate (per 100,000 people) of prostate cancer in Japan is looked at, it is only 3.5 for 1956, but 8.5 for 1990, and is statistically estimated to reach 20.3 in 2015.
In North America, the incidence rate of prostate cancer is strikingly high, and is 92.4 for 1990, and third-generation Japanese in the United States have an incidence rate of prostate cancer close to that of Caucasians in North America. It is not too much to say, also from this fact, that the westernization of life style including a meal with excessive fat is linked with the increase in prostate cancer in Japan. Thus, it is predicted that the prostate cancer of 80,000 to 100,000 people will be amenable to treatment in 2015.
Statistics by NCI (National Cancer Institute) in 1998 to 2002 show that the age-adjusted incidence rate (per 100,000 people) of cancers for all sites was 469.7 in the United States. Among these cancers, prostate cancer has the rate of 76.0, holding the first rank, followed by breast cancer (73.3), pulmonary or bronchial cancer (61.0), large bowel cancer (38.3), and lymphoma (21.8) which hold the 5th rank or above. Prostate cancer is characterized in that androgen induces the growth thereof while removal of androgen suppresses the growth. Therefore, in order to suppress the growth of prostate cancer, the removal of the testes through surgery or the application of an anti-androgen therapy in which the function of the testis is inhibited by a pharmaceutical agent is often carried out. However, the anti-androgen therapy will result in the recurrence of prostate cancer at some future time although it can suppress the clinical progress thereof over a certain period of time (typically, 1 to 3 years). The hormone therapy results in a ten-year survival rate of 10% or less when metastasis is present in a distant organ (often in the bone).
For localized prostate cancer, radical total prostatectomy (including the removal of the regional lymph node in the pelvis) literally provides a radical therapy. In addition to surgical therapy, there are a wide choice of options from hormone therapy to radiation therapy including heavy particle irradiation and direct implantation of an acicular radioactive material in the prostate and to chemotherapy using anti-cancer agents, depending on the degrees of malignancy and progress of prostate cancer and the presence of the metastasis thereof.